OLED (Organic Light Emitting Diode) is a current-driven device, which is widely used in the field of display due to its advantages of self-luminescence, fast response, wide viewing angle, and being able to be formed on a flexible substrate, etc.
For an active-driven OLED display device, each sub-pixel includes an OLED pixel circuit in addition to the OLED.
With the development of OLED display devices toward high PPI (Pixels Per Inch), limited by the space limitations of sub-pixels, only the simplest 2T1C pixel circuit can be used to drive an OLED, and the threshold voltage compensation circuit can't be used. Therefore, the threshold voltage may be shifted, leading uneven luminance and poor display effect of the OLED.